EVENING UPDATE - RAINFALL AND THE MODELS.

The modelling as mentioned in this evening's video analysis is going to remain divergent as we move forward. The high amplitude, complex nature of the weather pattern coupled with near record humidity values and widespread low pressure means that many areas will see unseasonal Summer rainfall and severe weather potential.


Some areas over the south and east could remain in severe weather risks for up to a week! That would be unprecedented, and this is due to the slack pressure pattern, with high pressure sitting well to the south of the nation.


So lets take a look at the short, medium and longer term weather details.


SHORT TERM

The placement of the rainfall has not changed that much from yesterday, however with the areas painted in for some decent falls, you will find that the heavier rainfall will move around. There is no skill in forecasting specific amounts in this environment, but giving a range of expectation is fair. But even then, your number will vary with thunderstorms moving around. Heaviest rainfall likely in a broad band from northwest WA through the NT, down into much of SA. In the east, scattered to numerous showers and thunderstorms return next week, with showers along the coast, but inland areas mostly dry for a while and humid. The weather focussing near the trough over SA. And QLD looking similar, showers for the coast and thundery weather over the far west. Finally, the monsoon will return to the north and I suspect rainfall totals may increase moving forward this week.


UKMET - Rainfall Next 7 Days - LOW CHANCE

Similar to last night and has the clear trough sitting over SA with heavy rainfall and thunderstorms. Some risk that the moisture stays out over SA and holds out passing into NSW and VIC, will watch that idea in the coming days. But for now the heaviest of the rain is expected over the northern tropics with a developing monsoon and the trough over the southern areas of SA extending north. Showers for the east coast.

ICON - Rainfall Next 8 Days - LOW CHANCE

Similar to above. Probably too dry for the southeast and east.

MEDIUM TERM

There is evidence of another wave of low pressure developing in the broad unstable and humid airmass later next week lingering into the following week, to end the month. Local flooding would then be an issue for southern, central and eastern inland Australia if this verifies. With the persistent moist and unstable signal for the nation, there is no reason as to why we will not see further showers and thunderstorms daily for large areas or an organised rain event. The monsoonal weather over the north of the nation will continue and may seep further south through the north and could be found between Broome and Mackay. That would lead to very wet weather nationally and moisture increasing into the SWLD of WA.


CMC - Rainfall Next 10 Days - MODERATE CHANCE

Has been very bullish in the idea of pulling moisture south from the NT and WA into a stationary trough over SA with torrential rainfall totals for Agricultural SA, but the weather could end up west of Adelaide with only scattered storms from there eastwards and severe weather over the EP, WC and NWP back to the southern NT and easter WA. Something to watch. Otherwise the monsoon will take hold of northern Australia.

EURO - Rainfall Next 10 Days

A very strong rainfall signal continues for large areas of the country and this idea is shared with the CMC with heavy falls coming into SA from the NT and WA. These falls would equate to some areas recording 4 months worth of rainfall in SA for outback areas and flood issues.

ACCESS - Rainfall Next 10 Days - LOW CHANCE

Has the trough a little further north in SA with heavy rainfall over the north and central areas of the state. A tropical system comes through WA and then moves southeast over the western interior. Heavy rainfall over interior parts of the NT and through to western QLD and into NSW. Scattered falls also for parts of VIC and southern WA. Note the tropical system over in WA increasing falls there.

KMA - Rainfall Next 12 Days - LOW CHANCE

Showing the trough in between the ACCESS and GFS solutions with record rainfall over SA and extending back through the NT and into QLD. A tropical feature may emerge over northwest WA. Widespread showers over the east of NSW and QLD. Lighter falls and humid for the southeast of the nation and dry out west.

GFS - Rainfall Next 16 Days - MODERATE CHANCE

Has been a little more consistent in the idea of more widespread rainfall, but the confidence remains low on a few items on the board, from the tropical feature up north to whether we see more troughs into the medium term lifting up the moisture for southern and eastern Australia.

ENSEMBLE DATA

I still like using the broader data sets and they are very wet for this time of year. February is the driest time of year for many southern and western interior regions and this is looking opposite as we end January and start of February.


GFS - Rainfall Next 16 Days (median of 35 members) - LOW CHANCE

The ensemble is less dynamic than the deterministic above however, with the high and near record levels of moisture in the atmosphere, some areas will see very heavy rainfall opportunities, exceeding what is being shown below.

CMC - Rainfall Next 15 Days (median of 30 members) - MODERATE CHANCE

This is probably more reflective of the major rainfall chances for SA and points north through the NT and up to the Top End with the monsoon. Also heavier rainfall is likely over the east and southeast with deep moisture and troughs nearby.

EURO - Rainfall Next 15 Days (median of 51 members)

The ensemble is more generous with the spread of rainfall but the falls are heavy over the north indicating the return of monsoonal weather. And for SA, those falls are quite outrageous, could be some of the heaviest Summer rainfall in the absence of tropical lows, in about 40 years.

LONG TERM

Very wet as outlined in the 6 week outlook earlier today.


CFS - Rainfall Next 6 Weeks - MODERATE CHANCE

More to come from 830am EDT tomorrow morning.